Not exactly your usual West End fare (after the bloody splatterfest, you might be feeling a little too queasy to face dinner à deux), Martin McDonagh's play is a hugely enjoyable black satire on the mindset that has led to cycles of violence and generations of misery in Ireland. Like Ben Elton's Popcorn, it heaps on the violence while condemning those who use it for their own ends. But McDonagh, in his best play to date, offers a more politically and dramatically coherent exposition of the way violence is glamorised and extremism infects people like a deadly virus.

Padraic is in the INLA, a splinter group of the IRA, but he is beginning to prove too extreme even for this organisation, particularly when he starts slicing of the nipples of the local drug dealer whose activities help fund the INLA's campaign of bombing. But Padraic has other things on his mind - the news from home that his beloved cat, Wee Thomas, is on his last legs. Returning to his home village, he sets in train a series of murderous events that might leave even your average vampire feeling slightly under the weather.

McDonagh is razor sharp on the absurdity of terrorists who quite happily torture and murder human beings, but are desperately concerned about the welfare of cats. He is even better on the easy eroticisation of violence that leads teenage girls to glamorise the likes of Padraic. There is some great stuff, too, on the accepting Irish mentality that allows all this to happen: when 16-year-old Mairead leaves home to join the INLA, her mother merely advises her: "Good luck and try not to blow up any kids."

This is a terrific play about a serious subject that's touched with a Monty Pythonesque insanity. It will liven up the West End no end. It strikes me as a pity that the producers didn't find a space for it that wasn't a traditional cross-arch theatre. All McDonagh's plays seem old-fashioned, and putting this one in a chocolate-box theatre robs it of impact, making it seem too safe and distanced - as does playing it with an interval.

There are no complaints, though, about Wilson Milam's racy production or the acting - which is to die for.